Kisspeptide in the estrous mare: is it an appropriate ovulation-inducing agent?

This research explored the use of a particular neuropeptide, kisspeptin, as an ovulation-inducing agent in mares. It found that it did not shorten the time between ovulation cycles, and the timing of administration could negatively affect sexual receptivity. Thus, the use of this neuropeptide for inducing ovulation may not be suitable for horses.

Introduction

• The study’s focus is on neuropeptides known as kisspeptins (KiSS). These have a central role in starting reproductive function in animals.
• The study aimed to figure out if mares could have a shortened interovulatory period by administering them an equine-special kisspeptin decapeptide named eKp-10.

Methods and Procedures

• The mares were segregated into three groups. Two groups were administered eKp-10 either on Day 16 postovulation or during estrus. The third group remained untreated, essentially acting as a control group.
• Every four hours, 0.5 mg of the eKp-10 was intravenously given to the mares.
• The researchers then assessed various factors such as the interovulatory interval, follicle diameter before ovulation, and the daily concentrations of FSH. This was done to compare the effectiveness of the hormone administration.

Observations and Results

• Neither of the two treated groups had a shorter interovulatory interval compared to the controls.
• No noticeable difference in follicle diameter before ovulation was found among the three groups.
• The hormone levels of FSH, progesterone and LH before ovulation weren’t significantly different across the groups either.
• The research also showed a negative correlation between the eKp-10 treatment start and sexual receptivity, and serum estradiol concentrations. Thus, suggesting that eKp-10 can disrupt the normal sexual receptivity in mares.
• This disruption, nevertheless, was brief (less than 72 hours). The overall change in sexual receptivity was also not significantly different between the treated groups.

Conclusion

• Contrary to findings in other species, the kisspeptin-triggered hypothalamic-pituitary mechanism was not found appropriate for horses.
• Administering eKp-10 to estrous mares might have been outside the hormone’s normal physiological context, making it an unsuitable candidate as an ovulation-inducing agent.